The present invention relates to a cryogenic liquefied gas tank for containing cryogenic liquefied gases such as natural gas or other petroleum gases which are in the gaseous state at room temperature and are liquefied by refrigeration at atmospheric pressure.
The tanks for the aforementioned purpose generally have rigid outer or inner vessels of a standing cylindrical shape which support the hydraulic pressure of the load of cryogenic liquefied gases contained therein. In accordance with the requirement for a larger capacity of the tanks in these years, the cylindrical tanks have gradually increased in diameter and height but they are now approaching the limit in view of the strength of the side wall and the roof and the difficulties encountered in construction techniques. Furthermore the construction of very large tanks brings about a safety problem.
At present, therefore, a large-scale storage area has a number of tanks placed with spaces between them, each being constructed to have as large a capacity as possible. However, when the tanks are placed adjacent to one another, the regulations generally require a relatively large space to be left between the tanks in view of ensuring safety in emergency, and, consequently, an extensive land area is required for the storage area, thereby substantially increasing its cost and reducing its economic merit.